Project description:The pathogenesis of primary hyperparathyroidism (I-HPT) and secondary hyperparathyroidism (II-PTH) remains to be elucidated. To characterize their pathophysiology, we investigated the effects of calcium and phosphate on cell proliferation and PTH release in an organ culture of parathyroid tissues. Dissected parathyroid tissues obtained from patients with I-HPT (adenoma) or II-PTH (nodular hyperplasia) were precultured on a collagen-coated membrane for 1-4 week. After exchanging the medium for one containing various concentrations of phosphate, PTH release and [3H]thymidine incorporation were studied. In contrast to dispersed parathyroid cells cultured in a monolayer, calcium decreased PTH release in a concentration-dependent manner in parathyroid tissues. Furthermore, when parathyroid tissues obtained from II-PTH were precultured for 1-4 weeks, PTH release and parathyroid cell proliferation were significantly increased in high-phosphate medium. These phosphate effects were also observed to a lesser extent in parathyroid tissues obtained from I-HPT, but there was no significant difference between I-HPT and II-HPT. Microarray analyses revealed that mRNA levels of PTH, CaSR, and VDR were well preserved, and several growth factors (e.g. TGF-beta1-induced protein) were abundantly expressed in II-PTH. Using organ cultures of hyperparathyroid tissues, in which PTH release and CaSR are well preserved for a prolonged period, we have demonstrated that phosphate stimulates parathyroid cell proliferation not only in II-PTH but also in I-HPT. Although the mechanism responsible for phosphate-induced cell proliferation remains to be elucidated, our in vitro findings suggest that both parathyroid tissues preserve to some extent a physiological response system to hyperphosphatemia as observed in normal parathyroid cells. These data will be published in Journal of Bone & Mineral Metabolism. Experiment Overall Design: Two conditioned experimets, low vs. high phosphate medium, cultured for 1 and 4 days
Project description:The pathogenesis of primary hyperparathyroidism (I-HPT) and secondary hyperparathyroidism (II-PTH) remains to be elucidated. To characterize their pathophysiology, we investigated the effects of calcium and phosphate on cell proliferation and PTH release in an organ culture of parathyroid tissues. Dissected parathyroid tissues obtained from patients with I-HPT (adenoma) or II-PTH (nodular hyperplasia) were precultured on a collagen-coated membrane for 1-4 week. After exchanging the medium for one containing various concentrations of phosphate, PTH release and [3H]thymidine incorporation were studied. In contrast to dispersed parathyroid cells cultured in a monolayer, calcium decreased PTH release in a concentration-dependent manner in parathyroid tissues. Furthermore, when parathyroid tissues obtained from II-PTH were precultured for 1-4 weeks, PTH release and parathyroid cell proliferation were significantly increased in high-phosphate medium. These phosphate effects were also observed to a lesser extent in parathyroid tissues obtained from I-HPT, but there was no significant difference between I-HPT and II-HPT. Microarray analyses revealed that mRNA levels of PTH, CaSR, and VDR were well preserved, and several growth factors (e.g. TGF-beta1-induced protein) were abundantly expressed in II-PTH. Using organ cultures of hyperparathyroid tissues, in which PTH release and CaSR are well preserved for a prolonged period, we have demonstrated that phosphate stimulates parathyroid cell proliferation not only in II-PTH but also in I-HPT. Although the mechanism responsible for phosphate-induced cell proliferation remains to be elucidated, our in vitro findings suggest that both parathyroid tissues preserve to some extent a physiological response system to hyperphosphatemia as observed in normal parathyroid cells. These data will be published in Journal of Bone & Mineral Metabolism. Keywords: Organ culture experiments, dultured in low vs.high phosphate medium
Project description:Secondary hyperparathyroidism (SHP) is a common complication of chronic kidney disease (CKD) and correlates with morbidity and mortality. In this study we profiled microRNAs (miRNA) in parathyroids from different experimental SHP models and uremic patients and studied the function of specific miRNA using antagonizing oligonucleotides (anti-miRs). miRNA profiles established by small RNA deep sequencing showed that human, rat and mouse parathyroids share the same most abundant miRNAs. Principal component analyses clearly segregated parathyroids from SHP rats from normal rats, based on their miRNA expression profiles. Similar findings were observed in hyperplastic parathyroids from CKD patients compared to normal parathyroids from patients without kidney disease. We identifed specific parathyroid miRNAs that were dysregulated in all experimental SHP models studied. let-7i was decreased and miR-141 and miR-148a were increased in the parathyroids of rats with prolonged CKD induced by an 8 w adenine high phosphorus diet. Down-regulation of let-7 by anti-miRs increased PTH secretion in normal and in CKD rats, as well as in parathyroid organ cultures. Anti-miR-148 prevented the increase in serum PTH in CKD rats and decreased secreted PTH in parathyroid organ cultures. Our findings characterized parathyroid miRNA profiles and demonstrated conservation of the abundant miRNAs in different species. The evolutionary conservation of abundant miRNAs and their regulation in SHP suggest that miRNAs are important for parathyroid function and the development of SHP. Down-regulation of let-7 and miR-148 affects PTH secretion in vivo and in vitro, suggesting a role for these miRNAs in SHP. We propose that let-7 restrains while miR-148 promotes PTH secretion. In CKD, the decrease in parathyroid let-7 and the increase in miR-148 miRNAs may contribute to the development of SHP.
Project description:Transcriptional profiling of genes expressed in normal parathyroid glands (Normal) and adenomatous parathyroid glands from patients with primary hyperparathyroidism (PHPT). Stratagen Human Refernece RNA, pooled from 10 human cell lines, was used to identify genes, which are specifically expressed or suppressed in parathyroid tissue. Comparison between normal and tumor parathyroids shows genes that might be involved in hyperproliferation and PTH hypersecretion in tumors.
Project description:The parathyroid gland is one of the endocrine glands in the body and plays a key role in regulating calcium and phosphate homeostasis through the production and release of parathyroid hormone (PTH). Despite its physiological importance, research on the parathyroid gland remains limited due to its small size and concealed anatomical location. Previous studies have suggested that the parathyroid gland consists of principal cells, acidophilic cells, and other cell types. While recent studies have applied single-cell sequencing to investigate the rat parathyroid gland, a comprehensive analysis of cell subpopulations, gene expression differences, and rare cell types is still needed. Therefore, this study aims to further utilize single-cell sequencing technology to analyze the transcriptional profiles of different cell types in the normal rat parathyroid gland, refine the characterization of cellular diversity, and provide additional insights into the molecular landscape of the rat parathyroid gland.
Project description:Whole mouse genome microarrays from Agilent were used to determine expression profile of whole organ cervical thymus, thoracic thymus and parathyroid from Foxn1-GFP; Pth-Cre; R26dTomato transgenic mice.
Project description:Parathyroid hormone (PTH) and PTH-related protein (PTHrP) are involved in cachexia associated with chronic kidney disease and cancer respectively. Tumor-derived PTHrP triggers adipose tissue browning and thereby leads to wasting of fat tissue in tumor-bearing mice. Similarly, elevated in 5/6 nephrectomized mice, PTH stimulates adipose tissue browning and wasting. Mice lacking the PTH/PTHrP receptor in their fat tissue are resistant to wasting of both adipose tissue and skeletal muscle. Therefore, the PTH/PTHrP signaling in adipocytes should activate various pathways that contribute to hypermetabolism and muscle wasting.
Project description:To investigate genes modulated in the parathyroid glands by calcium, expression levels of mRNA for all genes expressed in parathyroid tissue explants (PTEs) obtained from patients with primary hyperparathyroidism (I-HPT) were analyzed by oligo-DNA microarray. PTEs obtained from 4 patients with I-HPT were precultured in normocalcemic medium (Ca++ 1.0-1.1 mM) for 7 days and then cultured in hypocalcemic medium (Ca++ 0.60 mM) or hypercalcemic (Ca++ 1.60 mM) medium for an additional 7 days. As expected, expression levels of mRNA for PTH and chromogranin A were decreased to less than 50% in hypercalcemic medium. Furthermore, oligo-DNA microarray analyses followed by GeneSpring GX analyses revealed that 7 genes were up-regulated by more than 2-fold and more than 30 genes were down-regulated by more than 1/2 in PTEs obtained from patients with I-HPT. Interestingly, 9 of these genes (up-regulated genes: chemokine ligand 8[CCL8], multiple C2 domain and transmembrane region protein 1 [MCTP1]; down-regulated genes: matrix metallopeptidase-9 [MMP9], B-box and SPRY domain-containing protein [BSPRY], nitric oxide synthase 2A [NOS2A], parathyroid hormone [PTH], cartilage acidic protein 1 [CRTAC1], chromogranin A [CHGA], and fibrin 1 [FBLN1]) were involved in calcium metabolism or calcium-signaling pathways in the parathyroid tissue. Unexpectedly, however, the expression level of mRNA for alpha-klotho was variable, and it was not constantly decreased in hypercalcemic medium under the present experimental conditions. Although it was not possible to use normal parathyroid tissue, this is the first reported study to have investigated the expression levels of mRNA for all genes in human parathyroid adenomas that are modulated by high calcium concentration in organ culture.
Project description:We investigate whether Cinacalcet treatment timed to the expression of its drug target; the Calcium-Sensing Receptor, could improve efficacy of treatment in secondary hyperparathyroidism. We found that proliferation rate of parathyroid glands of uremic rats was markedly reduced when Cinacalcet was administered in the early inactive phase compared to conventional timing early in the active phase. We use RNAseq of parathyroid tissue to investigate the possible mechanism behind this enhanced anti-proliferative effect.
Project description:Pulmonary hypertension (PH) is an incurable right heart failure disease. Parathyroid hormone (PTH) is secreted from the parathyroid gland and plays a crucial role in calcium homeostasis. PTH also acts on the cardiovascular system and affects cardiovascular prognosis. We assessed whether the regulation of PTH affected PH in a hypoxia (Hx)-induced PH mouse model. PTH treatment exacerbated right ventricular hypertrophy and right ventricular systolic pressure in Hx mice. Our data showed how is PTH effected for PH model murine lung.